title: Extinction of appetitive learning is disrupted by cycloheximide and propranolol in the sand maze in rats.
abstract: The present study investigated whether memory for extinction in an appetitive task (the sand maze) could be attenuated by administration of cycloheximide (protein synthesis inhibitor) or propranolol (β-adrenergic receptor antagonist). Ninety-day-old male Long-Evans rats were trained to retrieve a sweet cereal reinforcer from an open container in the sand maze. One day following this non-spatial training, rats received three extinction trials in which they were placed in the maze with the reinforcer present, but unattainable. Thirty minutes prior to the first extinction trial, rats received an intraperitoneal injection of cycloheximide (1mg/kg), propranolol (25mg/kg), or vehicle (1mg/kg distilled water). Twenty-four hours later, rats were tested in the sand maze with the reinforcer again available. Results from the test trial showed that both cycloheximide and propranolol groups found the reinforcer more quickly than controls. Two weeks later, rats were trained on a spatial version of the sand maze in which they had to search for a buried reinforcer using extramaze cues. Cycloheximide and propranolol groups learned this task significantly faster than the control group, demonstrating the long-lasting effect of cycloheximide and propranolol on the blocking of memory for extinction.
authors.affiliation: Neuroscience Program Muhlenberg College, Allentown, PA 18104, USA.
authors.forename: Joshua
authors.initials: J
authors.lastname: Cohen
authors.forename: Gretchen Hanson
authors.initials: GH
authors.lastname: Gotthard
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000704:Analysis of Variance; D000818:Animals; D001070:Appetitive Behavior / Q000187:drug effects; D003513:Cycloheximide / Q000494:pharmacology*; D005106:Exploratory Behavior / Q000187:drug effects; D005108:Extinction, Psychological / Q000187:drug effects*; D008297:Male; D018782:Maze Learning / Q000187:drug effects*; D011433:Propranolol / Q000494:pharmacology*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology*; D051381:Rats; D020318:Rats, Long-Evans; D011930:Reaction Time / Q000187:drug effects; D013037:Spatial Behavior / Q000187:drug effects; D013997:Time Factors
chemical_list: D000319:Adrenergic beta-Antagonists; D011500:Protein Synthesis Inhibitors; D003513:Cycloheximide; D011433:Propranolol